The present invention relates to a method and apparatus for controlling a clutch-transmission unit, especially of a motor vehicle equipped with an internal combustion engine, in which the internal combustion engine is adapted to be influenced by means of an output control device, such as a drive pedal, and the speeds of the transmission unit are automatically shifted at least as a function of the position of the drive pedal and of the engine rotational speed.
Customarily, an automatic transmission control is designed according to the following criteria: either it is to permit a drive which is as economic as possible or a drive which is as output oriented as possible. By reason of the properties of the Otto engine, it is not possible to fulfill both criteria at the same time. Consequently, frequently only a compromise between both extremes is realistic since a shifting program which is purely consumption-oriented, does not offer sufficient safety reserves in critical traffic situations and with a shifting program that is output oriented, the fuel consumption is too high.
A further possibility is the manual shifting between an "economy" and a "power" program, (Automobiltechnische Zeitschrift 85, Volume 6/1983, pages 401-405). This solution entails the disadvantage that the driver has to actuate first a shifting member before a corresponding shifting program is made available to him. A further disadvantage resides in the fact that only two alternative extremes are offered to the driver which permit either only a consumption-oriented driving manner or an output-oriented driving manner.
Furthermore, it has to be recognized as disadvantage that this automatic transmission unit cannot shift correctly as regards a given situation when driving through curves or during braking or during the transition into coasting operation (taking the foot off the drive pedal), because only the instantaneous drive pedal information is available to it from the driver as the sole information transmitter concerning the traffic situation. If the driver takes his foot off the drive pedal at the entry of a curve or prior to the braking or during the transition into the coasting operation, then the automatic transmission initiates a shifting-up. If the driver again gives gas at the exit of the curve or after the braking operation or after termination of the coasting operation, then the automatic system at first has to shift back or down before the driver obtains the requested output. This means loss in time, loss in driving comfort and therebeyond additional clutch and transmission wear.
In addition to the deterioration of the actuating comfort, a further disadvantage is the additional time loss for the "searching" and "actuation" of the shifting member in case shifting is to take place in a short period of time from the "economy" to the "power" program, for example, by reason of the traffic situation.
For avoiding the last-mentioned disadvantages, an automation of the manual switching is proposed in U.S. Pat. No. 4,353,272 (DE OS No. 28 11 574); a program control unit is then switched from consumption optimal to output optimal operation if the (instantaneous) deflection velocity of the drive pedal exceeds a predetermined value. As a result thereof, the disadvantages of the manual shifting are eliminated, however, at the expense of one of its advantages, i.e., the memory effect of the mechanical shifting member. For, by reason of the missing memory effect, the power-optimal shifting program must be requested anew by a rapid depressing of the drive pedal every time one should or must drive smoothly and speedily, which in the final analysis will result in an increased fuel consumption and a "jerky" drive.
Accordingly, it is the object of the present invention to provide a control system for a clutch-transmission unit which, starting from a shifting program that is as consumption-optimal as possible, adapts itself to the driving behavior of the driver and to the just-prevailing driving, respectively, traffic situation without the need that additional operating elements have to be actuated.
The underlying problems are solved according to the present invention in that a drive pedal signal, proportional to the position of the drive pedal, is detected cyclically and/or anti-cyclically; in that by means of the scanned drive pedal signal value, these drive pedal signal values, which are detected and stored over detecting or scanning intervals, are continuously updated; and in that a drive pedal activity signals, evaluating the driving style of a driver and/or a driving situation, are calculated from these stored drive pedal signal values and are used for influencing limit values for shifting decisions.
The advantages which are attained principally by means of the present invention reside in the fact that, by simple means, a control for a clutch-transmission unit is created which, starting from a shifting program that is as consumption-optimal as possible, adapts itself dynamically to the driving behavior of the driver and to the just-prevailing driving, respectively, traffic situation without the need for actuating additional operating elements. Owing to the "continuous" transition from the consumption-oriented shifting program to the power- or output-oriented shifting program, the driving performance can be made available to the driver at any given time which he requests whereby attention is always paid in all ranges to the lowest possible fuel consumption. In addition to the reduction of the fuel consumption, additionally, the driving safety is increased, and more particularly, by the shifting operations carried out correctly from the situation point of view, thus also in curves, during braking and in coasting operation. By reducing the shifting operations, the transmission and clutch wear is reduced and the driving comfort is additionally increased.